1. Field of the Invention
This invention relates to a sliding clasp fastener and more particularly to improvements in coupling elements used therein.
2. Prior Art
Sliding clasp fasteners or zippers find extensive application on garments, shoes, bags and other daily commodities as well as on industrial materials and products.
It has been a common practice to apply certain lubricating materials such as paraffin to the coupling elements of the fastener as and when the same fails to function smoothly in use. This was done by coating or otherwise depositing such lubricating material on the exposed outer surface of the fastener elements. The lubricating material thus applied was susceptible to separation from the elements under the influence of external physical forces exerted when cleaning, or by the chemical action of cleaning solvents in cleansers, or by repeated impinging contact of the coupling heads of mating elements during opening and closing of the fastener. As a result, the fastener would malfunction or even become inoperative.